FIG. 18 is a cross-sectional view for explaining a method for manufacturing a conventional magnetic recording medium.
First, there is prepared a substrate to be deposited 100 in which at least a magnetic layer 102 is formed on a nonmagnetic substrate 101, and on the substrate to be deposited 100, a DLC (Diamond Like Carbon) film 103 having a thickness of 3 nm is deposited by a plasma CVD (chemical vapor deposition) method. Next, on the DLC film 103, a CN film 104 having a thickness of 1 nm is formed by sputtering.
Subsequently, by dipping the CN film 104 in a fluorine-based Fomblin oil, the Fomblin oil is coated on the CN film 104. Next, the substrate to be deposited 100 is annealed at 150° C. for 1 hour, and thus a fluorinated organic film 105 having a thickness of 4 nm that functions as a solid lubricant is formed on the CN film 104. In addition, as a method for producing the fluorinated organic film 105, an evaporation method is also used in some cases and the evaporation temperature in that case is 110° C.
When the magnetic recording medium is to be used, it is necessary to bring a media head (not illustrated) close to the fluorinated organic film 105, and the distance between the media head and the magnetic layer 102 is required to be shorter. Consequently, the total thickness of the DLC film 103, the CN film 104 and the fluorinated organic film 105 is required to be smaller.
Furthermore, the reason why the DLC film 103 is deposited by a plasma CVD method in the magnetic recording medium is as follows.
When a DLC film is formed by sputtering and the thickness is set to be 8 nm or less, there is generated a problem in which impurities such as Co are eluted from the magnetic layer 102 and the resultant impurities reach the fluorinated organic film 105 (so-called corrosion). Therefore, by depositing a DLC film by a plasma CVD method, a DLC film having a higher density than in the case of sputtering can be deposited, and thus, even when the thickness is set to be 3 nm, barrier properties for preventing corrosion can be sufficiently secured.
Furthermore, the reason why the CN film 104 is formed in the magnetic recording medium is as follows.
Since the contact angle of water with the DLC film 103 is about 80°, when the fluorinated organic film 105 is coated on the DLC film 103, the adhesion between the DLC film 103 and the fluorinated organic film 105 is poor. Consequently, the fluorinated organic film 105 cannot be coated on the DLC film 103. Therefore, by forming the CN film 104, with which the contact angle of water is about 30°, between the DLC film 103 and the fluorinated organic film 105, the adhesion between the DLC film 103 and the fluorinated organic film 105 can be enhanced. However, the CN film 104 does not have a barrier function for preventing the corrosion.